Surgical procedures that excise tissue or repair of tissues that are separated or disrupted often require suturing or staples to join the free ends of the tissue again to form a close seal for healing of the tissues. In some instances, the tissues must be connected tightly enough to prevent fluids or materials contained on one side of the attached tissue from leaking through to the other side of the tissue or from entering a surrounding body cavity. Maintaining the structural integrity of the original tissue at the repair site is a goal in creating the repair site. Surgical repair of gastrointestinal tissues, particularly after excision of tissue or growths, often results in repair sites that do not sufficiently seal the tissues to prevent leakage of intestinal materials into the surrounding peritoneal cavity.
Treatment of colorectal diseases may require surgical intervention include such diseases as colorectal cancer and inflammatory bowel disease (IBD) among others. In the United States, approximately 143,000 and 1.4 million people suffer from colorectal cancer and inflammatory bowel disease (IBD), respectively (National Cancer Institute and Centers for Disease Control and Prevention). Thus, every year, over 600,000 people in the United States will undergo surgical procedures to treat a number of colorectal diseases such as colorectal cancer, inflammatory bowel disease (IBD), and diverticulitis (inflammation of pouches formed on the other side of the colon) ([19, 20). Patients undergo either conventional open surgery or laparoscopic surgeries to remove diseased tissue[21]. These patients require end-to-end anastomoses of the healthy sections following removal of diseased segments (FIG. 1). Surgical suturing and stapling are still the most common and important procedures in colorectal anastomoses[22, 23]. However, both methods rely on piercing healthy tissue and can cause anastomosis leakage. Leakage of intestinal bacteria from the bacteria-rich colorectal system into abdominal lumen can cause serious infection leading to potentially deadly peritonitis[3, 4, 6, 24]. It is reported that one-third of the mortality after colorectal surgery is due to anastomosis leakage[25]. Alternative or supportive anastomosis methods are urgently required in order to decrease leakage rate and promote tissue regeneration after colorectal surgery.
Laser tissue welding (LTW) has emerged as a “sutureless” surgical method for the anastomosis of ruptured tissues (e.g. vessels, bowel, urinary tract, skin and others)[7-15]. In LTW, laser light is absorbed by the tissue, which converts it into heat energy, resulting in the alteration of tissue proteins[14, 16]. Fusing of the photothermally altered tissue proteins via covalent and electrostatic interactions[11, 17, 18] is thought to be the primary mechanism responsible for welding (fusing) tissues. However, the efficacy of LTW is severely restricted due to lack of effective bioadhesives that fuse tissues. Specifically, laser irradiation of tissues can result in photothermal conversion of light to heat, resulting in denaturation/structural change of proteins, which fuse at the weld site. This process results in improved tensile strength of the closure and minimized peripheral tissue destruction. The advantages of laser-assisted tissue welding (LTW) over conventional suturing and stapling include short operation times, immediate fluid-tight sealing, reduced foreign-body reactions (e.g. inflammatory response) and scar formation and accelerated healing[10, 26-30]. Concerns associated with LTW include insufficient anastomoses strengths due to sub-optimal bioadhesive performance, limited light penetration depth, and peripheral tissue thermal damage.
Accordingly, there is a need for materials and methods that can connect disrupted tissue using a light source. Such materials and methods are disclosed herein.